Polyphenylene ethers are excellent not only in mechanical properties, electrical properties and heat resistance but also in dimensional stability and hence are used for various purposes. The polyphenylene ethers, however, are poor in molding processability by themselves. For improving their molding processability, a technique of blending a polyamide has been proposed and the polyphenylene ethers have become materials used for a wide variety of purposes. Conductivity has recently been imparted to polyamide-polyphenylene ether alloys, and employment of such alloys in the exterior trim parts (e.g. fender and door panels) of automobiles which can be subjected to electrostatic coating is in rapid progress.
Characteristics required of materials for the exterior trim parts of automobiles are, for example, various characteristics such as conductivity, impact strength, heat resistance and fluidity which are sufficient to conduct electrostatic coating. Regarding the levels of such characteristics required for electrostatic coating, patent document 1 (corresponding to patent document 2 and patent document 3), for example, describes that the Izod impact strength is preferably more than 15 kJ/m2 and that the volume inherent resistance is preferably less than 106 Ω·cm.
With regard to a technique for imparting conductivity to a polyamide-polyphenylene ether alloy, patent document 4, for example, describes that the surface resistance can be reduced by blending carbon black. In addition, patent document 1 (corresponding to patent document 2 and patent document 3) discloses a resin composition comprising a blend of a compatibility-imparted polyamide-polyphenylene ether base resin and conductive carbon black and a production process of the resin composition. Patent document 5, patent document 6 and patent document 7 disclose resin compositions which comprise a polyphenylene ether, an impact strength improver having ethylenically unsaturated structural units, a compatibilizer, two or more polyamides and conductive carbon black or carbon fibril, and have a volume resistivity and an Izod impact resistance in specified ranges. Furthermore, patent document 8 discloses a resin composition comprising a polyphenylene ether, a polyamide, a specified amount of a compatibilizer and a specified amount of conductive carbon black or carbon fibril, and having a volume resistivity of less than 100 kΩ·cm. Patent document 9 and patent document 10 disclose resin compositions comprising a polyphenylene ether, a polyamide, talc and carbon fibril. Patent document 11 discloses a resin composition formed by adding a polyamide and carbon fibril to a first mixture comprising a polyphenylene ether, a polyamide and an impact modifier. Patent document 12 discloses a process for producing a resin composition comprising a polyamide, a polyphenylene ether and a carbon black concentrate by the use of an extruder having a L/D ratio lower than a specified value. Patent document 13 discloses, for example, a resin composition comprising a polyphenylene ether copolymer, a polyamide and a conductive filler.
Patent document 14 (corresponding to patent document 15) discloses a technique for improving conductivity by further adding organic ionic species together with a conductive filler to an organic polymer matrix. In addition, patent document 16 discloses a technique in which a carbon filler for conduction is made present in a polyphenylene ether. Patent document 17 (corresponding to patent document 18) discloses a technique in which conductive carbon black is made present in the sea phase of a resin composition having a sea-island structure formed by two thermoplastic resins, and conductive carbon black or hollow carbon fibril is made present in the island phase.
However, in these techniques, a large amount of a conductive filler such as carbon black should be blended in order to impart conductivity sufficient to conduct electrostatic coating, so that the fluidity is deteriorated. This problem has heretofore been pointed out.
Moreover, further improvement of the fluidity has come to be required with an increase in the size and shape complexity of the exterior trim parts of automobiles. Compositions obtained by conventional techniques, however, cannot easily have both a high fluidity and a high conductivity which satisfy the above requirement.
In addition, since polyamides are characterized by their water absorbability, a molded body formed from a polyamide-polyphenylene ether alloy changes in size owing to water absorption. Therefore, there has been a desire for a technique for effectively reducing the water absorption percentage and the size change caused by the water absorption.
Patent document 1: JP-A-8-48869
Patent document 2: U.S. Pat. No. 5,741,846
Patent document 3: U.S. Pat. No. 5,977,240
Patent document 4: JP-A-2-201811
Patent document 5: U.S. Pat. No. 5,843,340
Patent document 6: U.S. Pat. No. 6,171,523
Patent document 7: U.S. Pat. No. 6,352,654
Patent document 8: U.S. Pat. No. 6,221,283
Patent document 9: U.S. Pat. No. 6,469,093
Patent document 10: US-A-2002/183435
Patent document 11: U.S. Pat. No. 6,486,255
Patent document 12: US-A-2002/149006
Patent document 13: US-A-2003/92824
Patent document 14: JP-A-2004-513216
Patent document 15: U.S. Pat. No. 6,599,446
Patent document 16: WO-A-01/81473
Patent document 17: JP-A-2003-96317
Patent document 18: US-A-2003/130405